Investigation of mechanical and tribological properties of hybrid green eggshells and graphite-reinforced aluminum composites

Abstract

Low cost, low density and good thermal stability of hens' eggshells make them a new reinforcement material. Further, eggshell (Es) is considered as a renewable eco-friendly material. Besides, its waste causes insect infestation and therefore pollution problems. Graphite (Gr) is one of the most commonly used reinforcements due to its self-lubricating properties. Hence, the current work aims to use the powder metallurgy technique to fabricate various aluminum matrix composites having different weight percentages of hybrid green particles (eggshells and graphite). Sintering additives such as magnesium and tin were used to improve the density. Firstly, the powders were manually mixed and cold compacted at 475 MPa and then sintered at 630 °C for 2 h. A pin-on-disk wear, Vickers hardness and compressive strength tests were used to investigate the mechanical and tribological properties. Scanning electron microscope (SEM) was used to characterize the morphology and microstructure of the produced composites as well as wear mechanisms. Energy-dispersive X-ray spectroscopy (EDX) test was used to investigate the elemental composition of the composites. The results showed that adding graphite to the aluminum matrix composite containing eggshell has a positive impact on the tribological properties of the composite up to a certain limit (1.5 wt%). However, the additional increase in graphite content has an adverse effect. Hybrid composites with 3 wt% eggshell show the best compressive strength and hardness, whereas hybrid composite with 9 wt% eggshell has the lowest compressive strength and hardness. The mass loss of the hybrid composite increases with the increase in the graphite weight percentages regardless of the eggshell weight percentages. The combination of SEM micrographs and EDX showed signs for three wear mechanisms: abrasive, adhesive and delaminated wear in the examined composites.

Tribological Performance of Composites Reinforced with the Agricultural, Industrial and Post-Consumer Wastes: A Review

“…However, these types of matrices are often characterized by low hardness and limited tribological properties, which limits their possible application. Hence, there is still a need to create metal-based composites reinforced with appropriate agricultural fillers, enhancing both mechanical and tribological properties of the produced materials [ 2 ]. All of the studied metal matrix composites reinforced with agricultural waste materials are presented in Table 1 .…”

“…Among various metal materials used for tribological applications, aluminum and its alloys are one of the most commonly studied. However, these types of materials are characterized by low hardness and limited tribological properties, which, in turn, limit the possibilities of their application [ 2 ]. The most popular way to increase the strength of aluminum and its alloys is to add insoluble reinforcement to create a metal matrix composite.…”

Tribological characteristics of AA7075 composites reinforced with rice husk ash and carbonized eggshells

“…Moreover, wear rate decreased with increasing RHA content in composites for all ranges of varying RHA size. Alomani et al 40 investigated the mechanical/tribological properties of green hybrid aluminium composites reinforced with eggshells and graphite particles wherein the researchers reported that maximum hardness and compression strength was exhibited by hybrid composite with 3 wt% of eggshells and these properties decreased as the concentration of eggshells increased up to 9 wt%. Also, mass loss in hybrid composites varied directly with weight percentage of graphite irrespective of weight percentage of eggshells.…”

Microstructural and mechanical characterization of lamb bone ash and boron carbide reinforced ZA-27 hybrid metal matrix composites

“…Results showed that composites containing 3 wt.% B 4 C and 7 wt.% fly ash has higher hardness, tensile strength and wear resistance than unreinforced alloy. Almomani et al 18 found that eggshells (ES) and graphite (Gr) reinforced Al-based hybrid composites have higher compressive strength, hardness, and wear resistance than single reinforced composites. Durowoju et al 19 evaluated the mechanical properties of hybrid Gr-Al composites incorporated with ES, Si, and SiC particles.…”